Ключевые слова: abstract, algebra, background, blackboard, board, calculate, calculation, chalk, chalkboard, college, complex, computation, doodle, drawing, educate, education, equation, formula, function, geometric, geometry, handwriting, handwritten, icon, illustration, knowledge, learn, math, mathematical, mathematics, parabola, pattern, physics, relation, retro, school, science, seamless pattern, sign, sketch, solution, study, symbol, texture, theory, trigonometry, university, wallpaper, white,